1. Field of Invention
The present invention relates broadly to intravenous needle assemblies (catheter placement assemblies) and more particularly to needle assemblies comprising a hypodermic needle with a pointed end and a hub secured along the blunt end thereof, the hub carrying a transparent blood detection or flashback chamber so that the proper introduction of the needle into the vein can be ascertained by a showing of blood from said needle, within the blood detection chamber, while simultaneously permitting entering blood and displacement of air, but not blood from the interior of the detection chamber.
2. Prior Art
Heretofore, intravenous needle assemblies have employed metal needles and hubs, sometimes permitting no visual observation of blood following venipuncture until blood flows from the trailing end thereof. In other instances, transparent flashback chambers have been provided integral with a hub to permit early detection of the blood after it passes beyond the needle of the intravenous needle assembly. Still other such assemblies have employed plugs with an air removal feature. Some of these are not effective to reliably evacuate air; some require a separate operation to provide a uniform slit in a radial diaphragm. See U.S. Pat. No. 3,859,998. Such slits are expensive to produce and the end product is not of consistent reliability. Consequently, it has been a long standing problem to dependably produce air breather caps which are economical and effective to exhaust air while obviating blood loss following venipuncture. Additionally, the methods of producing breather caps or plugs are expensive and have sometimes created safety problems, e.g. the danger of loose particles. Further, prior art air bleed plugs contain a single narrow opening which may in any particular use be so oriented or clogged as to not permit full evacuation of air from the interior of the intravenous needle assembly.